May 29, 2009
Evidence For Vitamin D As Alzheimer's Risk Reducer

A scientist argues for prospective studies in the ability of vitamin D to cut the risk of Alzheimer's Disease.

Amsterdam, The Netherlands, May 26, 2009 There are several risk factors for the development of Alzheimer's disease and vascular dementia. Based on an increasing number of studies linking these risk factors with Vitamin D deficiency, an article in the current issue of the Journal of Alzheimer's Disease (May 2009) by William B. Grant, PhD of the Sunlight, Nutrition, and Health Research Center (SUNARC) suggests that further investigation of possible direct or indirect linkages between Vitamin D and these dementias is needed.

Low serum levels of 25-hydroxyvitamin D [25(OH)D] have been associated with increased risk for cardiovascular diseases, diabetes mellitus, depression, dental caries, osteoporosis, and periodontal disease, all of which are either considered risk factors for dementia or have preceded incidence of dementia. In 2008, a number of studies reported that those with higher serum 25(OH)D levels had greatly reduced risk of incidence or death from cardiovascular diseases.

Several studies have correlated tooth loss with development of cognitive impairment and Alzheimer's disease or vascular dementia. There are two primary ways that people lose teeth: dental caries and periodontal disease. Both conditions are linked to low vitamin D levels, with induction of human cathelicidin by 1,25-dihydroxyvitamin D being the mechanism.

There is also laboratory evidence for the role of vitamin D in neuroprotection and reducing inflammation, and ample biological evidence to suggest an important role for vitamin D in brain development and function.

This could be done with either blood tests of vitamin D levels or vitamin D supplementation.

Given these supportive lines of evidence, Dr. Grant suggests that studies of incidence of dementia with respect to prediagnostic serum 25(OH)D or vitamin D supplementation are warranted.

The advantage of vitamin D supplementation over blood tests is that high blood vitamin D might be a marker for other things that reduce risk of Alzheimer's. For example, a person with a more slowly aging brain might get outside more often, get more sunlight on their skin, and therefore have more vitamin D in their blood. Or diseases could lower blood vitamin D and also increase risk of Alzheimer's at the same time.

The problem with prospective studies is that they cost a lot and take a long time. You really do not want to find out 10 or 15 or 20 years from now that vitamin D is protective since damage that leads up to an Alzheimer's diagnosis probably begins many years earlier. People in middle age and later need to cut their disease risks starting now. Since I do not want to wait for the evidence to become definitive I'm already taking vitamin D.

Share |      Randall Parker, 2009 May 29 11:41 AM  Aging Diet Brain Studies


Comments
Nick G said at May 29, 2009 1:41 PM:

People differ in how their skin produces Vitamin D, and how they process supplements. You should really test your blood serum levels to guide your program of supplementation.

It's 10 PM. Do you know where your D levels are?

got milk? said at May 30, 2009 5:03 AM:

Do you really need to do that at under 2000/day?

Nick G said at May 30, 2009 10:03 AM:

Actually, the risk of not enough D is probably greater than the risk of too much.

I found that I needed 10,000 iu/day to get my levels up to where they should be. Very few physicians have kept up with this, and they almost always recommend too little D.

Ted Hutchinson said at May 30, 2009 12:53 PM:

Grassrootshealth.org offer as part of a trial $40 postal 25(OH)D testing. It's a simple finger prick test requiring only 2 drops of blood on a sample sheet. You mail this back to the lab and in a few days the results are posted online.
Most UK readers average about 50nmol/l~20ng through the year and the least incidence of chronic illness is generally found above 137.5nmol/l ~ 55ng so most UK adults will need to take about 5000iu/daily to achieve that. It takes a while to raise status so after about 3 months it's worth getting tested. You'll then be able to see if you've reached a safe level.
Vieth has shown that 10,000iu/daily is a safe upper limit even in places where Vitamin D can be made regularly from sunshine.

Micha Elyi said at May 31, 2009 6:28 PM:

Notice that the 10,000IU/day upper limit in Vieth is for D(3) (cholecalciferol). D(3) is usually produced from animal products, typically fish oil. The vegetarian vitamin D supplements are most often D(2) (ergocalciferol). The D(2) form may also have a far lower safe upper limit and has one-third of the bioavailability of D(3). Symptoms of vitamin D overdose may not appear until weeks or even months after beginning a supplementation regimen because vitamin D can accumulate in the body's fatty tissues.

This comment is not medical advice and is supplied for information purposes only.

Edward Hutchinson said at June 7, 2009 12:43 PM:

Risk Assessment Vitamin D sets out the evidence for both D2 and D3.
Vitamin D2 rip-offs shows only health professionals are so willingly misled, most people have more sense than to pay considerably more for a substance that is undoubtedly worse value for money.
Twice yearly 25(OH)D testing will enable people to monitor their intake to ensure 50~70ng 125~175nmol/l is attained and maintained throughout the year. Unfortunately the entire UK adult population averages 50nmol/l through the year about a third of the ideal amount so the chance of toxicity in a country where almost everyone is deficient really isn't something one has to be concerned about. When we can see most of the population have attained adequate status then maybe we will have to worry about mega dosing, but providing people never take more than the amount that could be made in one day living naked outdoors for long periods, it is unlikely adverse events will occur.
Worrying about vitamin d toxicity when all around are suffering from insufficiency states is a bit like worrying about drowning while dying of thirst in the desert.

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